Figure 2.

Different types of repairs fix different types of DNA damage caused by IR. Through direct effects involving the deposition of ionizing energy in the DNA itself or indirect effects involving the absorption of ionizing energy by water, leading to the production of water radicals and their subsequent reaction with DNA, IR induces several types of damage to DNA. While IR induces a variety of DNA damages, the DNA DSB is a main lesion responsible for the aimed cancer-cell killing in radiotherapy. DNA repair machineries in response to different types of IR-triggered DNA damage are illustrated.